Electromagnetic relay



Get. 2, 1928. I 1,685,953

G. A. E. LUNDELL ELECTROMAGNETIC RELAY Original Filed March 21, 1921 9 Patented Get. 2, 1928.

, 1 UNITED s'r ATES' 4' 1,685,953 PATENT OFFICE.

GEORGE} ALEEN Ej-LUNEELL, or NEW YORK, N. JEANNETTE noLoEEs LUNDELL EXECUTRIX'OF SAID GEORGE ALEEN E. LUNEELL, DECEASED.

ELECTROMAGNETIC R LAY A nbationfaiea March 21,1921. Serial This invention relates to electro-niagnetie relays; and more particularly to electro-magonetic relays having two distinct operative eretofore in relays'of the two-steptype,

the partial energization ofthe relay upon bringingjthe relay armature intoits first operative positionhas caused the circuit controlling springs macaw thesecond step tozbecome partially operated, thus aflecting the reliability of the ,contacts,established by such springs andintroducin such chances oftrouble that relays of this type have not come into extensive commercial use.

As is well known to those skilled in the telephone art it is the practice to. provide for each subscribers line aso-called line relayv which-responds to the lifting of the receiver fromits hook when originating-a call, and a Vcut-ofl' 'elayl".wliicli operates when the operator connects tothe line one of the plugs provided for thatpurpose. In 'thedisclosure hereinsetforth, the relay of the present inventionperforms both of these functions, as'it responds to the lifting of the receiver when originating-a call by assuming its first operative stepand tothe connection ofan operators plug with the line by assuming its second operative step.

. In-combined line and cut-oft relays of the prior art, the partial energi-zatlonof the relay; magnet-icfield responsive/ to the lifting 'o'fjthe receiver when'originating a call ,encyto buzz and rendering has wcakenedthe contact pressure of, the cut-off? springs,=thus introducing a tendthe' operation manifestlyunreliable;'

It is the'object of the presentsinvention to enable the; circuit controlling springs .to establish contacts of improved dependability irrespective of whether the relay is in its normal, the first step 1 or in the second step. Another feature of the present invention provides two armaturesfwhich. move, when attracted. in opposite directions and whose attractive efforts neutralize-each other when a the currcntjis below a predetermined point. The said arniatures have air gaps, which are normally maintained openby springs of relatively different tension. Thus the weak current attracts the armature so maintained by the weak spring and fthearinature having the strong spring can only actuate when the current strength is sufficiently great so that, the fieldiof magnetic force causes the No. 453,958. Renewed August 31, 1927.

magnetic circuit of one of said armatures to. become super-saturated magnetically. Thus whlle at weak current values, the efforts of the armatures'are differential on the contrary, at strong current values the efforts are unbalanced. I

A mass of paramagnetic material is understood to be saturated when it is magnet.- ized so that point beyond which a relatively great increase in magnetizing force is revquired to produce an appreciable increase in magnetic density. In: Hobarts Dictionary of Electrical Engineering, Volume 11, page 461 there is shown the point K in the figure, and it is approximately this point that is rneant by theterm saturation point in the tellowingdescription. i

According to another feature. of the invention the usual insulating spool head serves also as a stop to determine the movement of the armature away from the core. i

Relays of the two step type may be employed inelectrio control systemssuchas telephone or telegraph systems, for a variety of purposes. It is understood that the scopeof the invention is notto be determinedbv the specific disclosure, reference being bad to the appended claiinsfor that purpose In the drawings: Figure 1 shows a top spring assembly;

Figure 2 shows a side view of the relay with the armatures in place;

Figure'3 shows anend view of the contact springs and armatures; y r

Figure 4 shows the connecting end oft-he contact springs with parts broken away;

Figure 5' shows an armature having large. cross section area; 1 o a Figure 6 shows an end view ofthe armature of Figure 5 i Figure 7 shows an end View of the armature otsniall cross section area;

Figure 8 is a side view of the armature of Figure 7; V V

Figure 9 shows theconnecting endofthe springsoppositelysituated to Figure 4 and with parts broken away;

Figure 10 shows details of themagnetic circuit of "the relay and the supporting mem hers for the contact springs; and Figure 11 shows an end view of the connecting end of the relay.

The coil 21 forms an energizing winding upon a core 22 and is retained thereupon by view of thecontact the insulating spool heads 23, 24. The core 22, which may be of any suitable paramagnetic material is provided with a rearwardly extending portion 25 having the extensions 26, 27 which by means of suitable threaded screw holes are adapted to be rigidly secured to a supporting plate (not shown). Two arms 201, 202 are also provided for a purpose to be subsequently set forth.

Supported by the upper and lower extremities of the portion 25 by means of the spring plate 28 and lugs 33, is the armature 30. This armature 30 may be of any suitable shape of any suitable para-magnetic material, and one part thereof extends to a side of the forwardly extending pole-piece 36 of the core Mounted upon the same extremities of the portion 25 are respectively the circuit controlling springs 110, 111, 114, 115, 116 and the terminal post 134 in the upper group, insulated from each other and from the core 22 by suitable insulating plates and bushings and circuit controlling springs 105, 106, 203, 204 and the terminal post 109 in the other group, similarly insulated. Itis understood that any suitable arrangement or combination of such circuit controlling springs may be employed without departing from the spirit of the invention. The terminal posts 134, 109 are connected to the coil 21, it being understood that additional posts may be provided in a manner well known in the art, should they be required by the conditions in the circuit in which such relays may be used.

The circuit controlling springs are provided with the usual contact points to complete the circuit between them. Attached to the free end of the armature 30 are the insulating studs 44, 44. These studs 44, 44 serve to maintain the armature 30 at a distance from the pole-piece 36 because of tension in the circuitcontrolling springs 105, 115. Thus in the normal position there is an air gap between the armature 30 and the pole-piece 36. The retractive movement of the armature 30 is limited by the nut 40 and the washer 38, mounted upon the stud 37. The stud 37 is rigidly secured to the core extension 36.

hen the armature is moved towards the pole-piece 36 the studs 44, 44 serve to open or close the associated circuit controlling springs of the relay. In the relay of the present invention such movement of the armature 30 causes the contact between springs 115, 116, 110, 111, 105, 106 to be broken.

Supported by the arms 201, 202 by means of the spring plates 31, 31 is the armature 32. This armature 32 may be of any suitable paramagnetic material and may be formed in any suitable shape with acrosssection area substantially less than that of armature 30, and one part thereof extends to the side of the forwardly extension 36, 42

of the core 22 opposite to the side on which the armature 30 is situated. The forwardly extending pole-piece 42 has a cross section area substantially less than that of the core 22 and the portion 36.

Mounted also upon the arms 201, 202 are the separating plates 49, 49 and the butter springs 43, 43. A portion of each of the buffer springs 43, 43 rests upon the spool head 24 and said springs 43, 43 serve to limit the movement of the armature 32 away from the pole-piece 42. Suitable non-magnetic separators may be provided between said armature 30 and the pole-piece 36 and armature 32 and pole-piece 42.

Attached to the armature 32 are the insulating studs 46, 47 which extend to the springs 114, 205. These springs 114, 205 have a tension and thus serve to maintain the armature 32 at a distance from the extending portion 42 of the core.

Thus it will be seen that the magnetic circuit oi the relay consists of the actuating portion 22 in which there is set up a magnetic field of force. The return path for the magnetic lines of force consists of separate branches, one of relatively small cross section area consisting of the arms 201, 202, the armature 32, the pole-piece 42; and the other consisting of the portion 25, the armature 30 and the pole-piece 36. These return paths are in shunt with each other. The saturation point of the return path of small cross section area is less than that of the path with large cross section.

When the magnetic field set up in the actuating portion 22 is relatively weak the armatures 30 and 32 are attracted to the polepiece 36, 42, respectively. Being disposed on opposite sides of said extension the armatures 30, 32 tend to move in opposite directions. The armature 30 meets the opposition of the springs 105, 115, and on account of the relatively strong tension of these springs and the relatively weak magnetic field the armature30 is unable to move said springs 105, 115. The armature 32 meets and overcomes the opposition of the springs 114, 205 on account of the relatively weak tension of these springs. The spring 114 contacts with the spring 115 at a point midway between the point of engagement of the stud 44 with spring 114 and the contact points of the springs 115, 116.

Thus the pressure of the spring 114 against the spring 115 opposes and substantially neutralizes the pressure of the stud 44 and the contact pressure at the contact points between the springs 115, 116 and the springs 110, 111 remains practically constant. The reliability of said contacts is therefore substantially the same as when the relay was entirely deenergized. Similarly spring 205 presses against spring 105 and opposes the pressure of the stud 44 against tive efi'ort in the armature 32.

'thespring 105 and the contact pressure between the springs 105 106 remain practically constant.

\Vhen a strong magnetic field is set up in the actuating portion 22, on account of the low saturation point of the return magnetic path comprising the armature 32 this return path becomes saturated and the increase in the magnetizing force'above this saturation point produces practically no further attrac- The relatively larger cross section area of the return path comprising the armature 3O permits the increase in the magnetizing force to effectively attract the armature 30. This increased attractive force overcomes the tension of the spring 115', 105 and the opposition of the armature 32. It will be noted that the opposing force of the armature 32 is transmitted through the flexible springs 114, 205 so that armature 32 mayor may not retract or maypartly retract.

When the relay is de-energized its armatures are retracted under control of spring 11 1, 115, 205, 105. The relay is thus re-- stored to normal and available for subsequent use. I i g In the drawings the horizontal distances between armatures 30 and 32 and the polepiece are shown somewhat exaggerated. It is understood, however, that suitable air gaps in accordance with the attractive strengthof the relay may be provided. 7

Having thus describedthe invention, what is claimed is 2 1. In an electro-magnetic relay, a double pole-piece, an armature adjacent to one side of said pole piece, a spring retracting said armature, a stud secured to said armature at its free end and adapted to press against said spring at the free end, thereof, a contact spring normally maintained in electrical contact with said retractive spring at a point between said stud and the rigid end ofsaid retractive spring, a second armature adjacent to the opposite side of said pole piece, a spring retracting said armature, a stud secured to said armature and adapted to press against said spring, and a contact between said retractive springs for making contact between said springs at a point intermediate said first mentioned stud and the point of said electrical contact.

2. In an electromagnetic relay, a double pole-piece, an armature adjacent to one side of said pole-piece, a spring retracting said armature, a stud secured to said armature at its free end and adapted to press against said spring at the free end thereof, a contact spring normally maintained in electrical contact with said rctractive spring at a point between said stud and the rigid end of said retractive spring, a second armature adjacent to the opposite side of said pole-piece, a spring retracting said armature, a stud secured tosaid armature and adapted to press against said spring, and a contact between said retractive springs for making contact between said springs at a point intermediate said first named stud and the point of said electrical contact', one of said armatures havinga'magnetic circuit of relatively low mag- I netic saturation characteristics.

3.-In a two step relay, amagnet, an armature arranged to move a predetermined distance upon partial energization of said magnet, a second armature for disabling said first mentioned armature upon additional encrgization of said magnet, and means for counteracting buzzing action of said relay in the partially operated position of said relay. In testimony whereof, I have hereunto set my hand this 19 day of March, 1921.

GEORGE ALB'EN E. LUNDELL. 

